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Dark spots.. what am I dealing with here

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crushday

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As someone who just planted vines this year, and wanting to avoid “black rot” - how do you prevent this from happening? What causes it?
 

GreginND

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As someone who just planted vines this year, and wanting to avoid “black rot” - how do you prevent this from happening? What causes it?
Mike posted a really good link for information. Bottom line, you want to start a fungicide spray program early in the season before any signs or symptoms show up. Mancozeb is pretty effective at controlling black rot.
 

kartracer088

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Thanks for the great link above, I also found this from Ohio State University for
Homeowner Control of Grape Black Rot that supports the use of Mancozeb.

https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/b/37477/files/2017/04/Homeowner-Control-of-Grape-Black-Rot-Ellis-for-fact-sheet-addition-11vxx3a.pdf


I planted 7 Marquette vines and 9 Marechal Foch vines 3 years ago. I have just been pruning and training for the future. I was thinking this would be the year I would try to harvest some grapes. I didn't realize how important spraying apparently is. Up until now, I haven't used any fungicide sprays. It may be too late this season already to recover the clusters, we shall see. I went to the local nursery and they recommended the Bonide Fruit Tree spray. It lists grapes as one of the crops that can be treated with it. But the OSU seems does not mention any of the active ingredients. I don't know of a source for the other fungicides so I went ahead and treated the vines this morning with the Bonide Fruit tree spray, maybe, it will help.

Next year I will plan out the sprays better. Live and learn. This afternoon, I will go and manually remove as much of the infected clusters and plant that I can recognize.

Bonide Fruit Tree Spray.
upload_2019-6-30_10-56-15.png

Any other suggestions for recovering for this season?
 

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Masbustelo

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Try spraying with a dilution of potassium metabisulphate. It might dry up what you are looking at. But isn't black rot endemic at this point?
 

kartracer088

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Yeah I think it's water under the bridge at this point, we'll just see what happens and plan better next year.
 

bstnh1

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As someone who just planted vines this year, and wanting to avoid “black rot” - how do you prevent this from happening? What causes it?
Use protective fungicide sprays. Pesticides registered to protect the developing new growth include copper, captan, ferbam, mancozeb, maneb, triadimefon, and ziram. Important spraying times are as new shoots are 2 to 4 inches long, and again when they are 10 to 15 inches long, just before bloom, just after bloom, and when the fruit has set.
Cultivars with large, juicy berries are the most susceptible. In general, grapes that ripen late in the season are affected the least. Most commercial cultivars are sufficiently resistant if adequately protected with a fungicide spray program. ‘Baco #1’, ‘Cascade’, ‘Cayuga White’, ‘Chancellor’, ‘Chelois’, ‘DeChaunac’, ‘Elvira’, ‘Missouri Riesling’, ‘Norton’, ‘Vidal 256’, and ‘Verdelet’ are varieties which are moderately resistant.
 

Dennis Griffith

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Mike posted a really good link for information. Bottom line, you want to start a fungicide spray program early in the season before any signs or symptoms show up. Mancozeb is pretty effective at controlling black rot.
Mancozeb is a great product, but remember that it has a 66 day PHI. Also, read labels thoroughly before using any products. With grapes this far along, I'd use another product. Immunox is very effective for black rot and has a 14 day PHI. You may also want to consider adding Serenade to your spray mix. It is preventative and considered organic as it is biological. I've been using it for 2 years now and believe it is beneficial as part of a spray program. As for Mancozeb, I use it early and then again after harvest.
 

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